Connective tissue

Fibroblast and fibrocyte difference?

"fibroblast" denote the active cell and "fibrocyte" denote the quiescent. He active fibroblast has more abundant and irregularly branched cytoplasm, containing much rough endoplasmic reticulum (RER) and a well-developed Golgi apparatus, with a large, ovoid, euchromatic nucleus. The quiescent cell is smaller than the active fibroblast, is usually spindle-shaped, much less RER, and a darker, more heterochromatic nucleus

Proteoglycan - what is it (structure and function) and types (also where)?

-A glycoprotein containing a protein core with attached long, linear carbohydrate chains -Trap water in varying amounts, affecting the viscosity of the ground substance and allow adhesion types: -aggrecan in cartilage -perlecan in basal lamina

how do reticular fibers form and where they are located?

-Fibers made of collagen III by fibroblasts at reticular lamina -form network (reticulum) around adipocytes, smooth mm, nerves and vessels -abundant in bone marrow, spleen and lymph nodes

loose connective tissue (name, location, structures)

-also called areolar ct -beneath ephtiium of organs and b\w mm. and nn. -cells, fibers (collagen is still dominant but elastic and reticular fibers are also found) and ground substance equally found

GAG features (name, sugars, staining)

-also called mucopolysaccharides -made of either glocose or galactose -negative charge (hematixyon)

Multi-adhesive glycoproteins (structure, function) and types (also where)

-branched oligosaccharide chains -have multiple binding sites -forms insoluble networks through connective tissue that gives support types: -Laminin contains binding sites for integrins, type 4 collagen, and some specific proteoglycans -fibronectin contains binding sites for collagens, intergins and a variety of GAGs

How elastic fibers are formed

-by fibroblasts -microfibrils act as scaffold on which elastin is built -cross links held by desmosin ring

dense irregular connective tissue (structures, function, location)

-fewer cells, more type I collagen -fibers in random direction to prevent stress from all directions -deep dermis and organ capsules

dense regular connective tissue (structures, function, location)

-fewer cells, more type I collagen -fibers in the same direction to resist repeated stress -tendons, aponeurosis, ligs

Tendinocytes are? is it possible to see them with H&E?

-fibroblasts in tendon -difficult to see with H&E

mast cell secretions

-histamine (increasing permibility) -heparin (sulfated gag preventing clotting) -serine proteases (inflamation mediator) -cytokines (inflamation mediator) -reactive lipid (inflamation mediator)

types of GAG (size, location of synthesis)?

-hyaluronan (large, direct to ECM) -derm\chond\ker\heparan sulphates (smaller, dissacharide units, RER)

marcophages features (nucleus, size, diiferent name, father cell, orgenells)

-nucleus: eccentric and kidney shape -size: vary according to activity -name: also called histocyte -father cell: monocyte -organells: developed golgi and many lysosomes

plasma cells features (nucleus, size, father cell, organells)

-nucleus: eccentric and spherical shape (cartwheel) -size: vary according to activity -father cell: B lymphocytes -organells: developed golgi and RER, basophilic cytoplasm

mast cell features (nucleus, size, similar cell, color, stain, location)

-nucleus: huge -size: vary according to activity -most similar to: basophils (mast cells have basophilic secretory granules) -color: metachromatic stained with different color then the dye stain: pas positive -location: mainly near skin vessels, mesenteries, digestive and resp mucus

Reticulin is? how is it produced?

-reticular fiber that supports hemopoietic ograns such as the spleen and lymph nodes -produce by modified fibroblasts

elastic fibers regarding collagen (size, stain, material)?

-thinner then type I -stained more dark then collagen -made of fibrils\fibrillin (and not fibrins)

Collagen Families

1) fibril forming (aggregate from smaller fibrils) - SCAB -type I - STaBeD (resist tension) -type II - resist pressure -type III - expansion (associated with type I) 2) network forming -type IV - support epihthilia and basal lamina 3) anchoring -type VII - anchoring basal and reticular lamina

collagen synthesis steps

1. DNA is transcribed (to mRNA) in nucleus 2. mRNA is translated (to pre-procollagen) and enter RER by signal sequence 3. Pre-procollagen will be modified to procollagen in RER (addition of hydroxy to proline and lycine by hydroxylase and glycosilation) - At ends of procollagen chains, propeptides (usually aren't part of helix) added to prevent spontaneous formation collagen fibers in cell, they are held by SS bridges 4. Procollagen secreted to ECM by exocytosis 5. Procollagen peptidases cleave propeptides to form tropocollagen 6. Newly formed tropocollagen molecules spontaneously self assemble to form fibrils 7. reinforced by Lycyl oxidase that forms covalent bonds

which ground substance are the following: 1. hyaluronan 2. perlecan 3. laminin 4. fibronectin 5. aggrecan 6. derm\chond\ker\heparan sulphates

1. GAG 2. PG 3. GP 4. GP 5. PG 6. GAG

associate diseases with CT structure: 1. edema 2. aneurysm 3. keloid (large raised scars\masses in the skin) 4. scurvy

1. interstitisl fluid 2. mutation in fibrillin gene and high BP that cause aortic swellness 3. swelling due to large amount of collagen forming scars of the skin 4. unstable procollagen as the vit c is required for hydroxylase activity

What is the staining of: 1. Gags 2. collagen 3.mitochondria 4.adipose tissue 5.elastic fibers 6. reticular fibers 7.glycogen

1.baso 2.acido 3.acido 4.sudan black 5.orcein 6.silver 7.pas

From what does ct originate?

All connective tissues originate from embryonic mesenchyme, a tissue developing mainly from the middle layer of the embryo, the mesoderm

type 5 collagen

Chorion and amnion as to types I II and III it is made of triple helix

Sulfated GAGs are important constituents of what extracellular structures? a. Hyaluronan b. Elastic fbers c. Type I collagen d. Proteoglycans e. Multiadhesive glycoproteins

D

What is an important part of the role played by macrophages during maintenance and renewal of strong extracellular fbers in connective tissue? a. Storage for a major energy source needed for ECM maintenance b. Production of specifc collagen subunits c. A sentinel function against invaders entering the ECM d. Secretion of matrix metalloproteinases e. Presentation of antigens important for assembly of collagen bundles

D

What secrets elastic fibers?

FB but also smooth mm that also makes coll I and III

Which collagen does epithelial make? What about other tissue secreting collagen?

IV by epithelial cells *smooth mm makes types I and III

what is mucoid tissue? which substances make it?

This tissue is an embryonic form of gel-like connective tissue with few cells (mesenchymal cells), best seen around blood vessels in the umbilical cord -has lots of ground substance, mainly hyaluronan,

How can elastic fibers can be seen?

With orcein dye

Type 4 collagen? structure?

basal lamina not helical, has lacunae

Collagen degradation by?

collagenases from MMP family (from macrophages) facilitate degradation, then by proeases

what is elastic lamellae?

elastic fibers in the tunica media (vessels)

fibroblasts involved in damage fix are called?

myofibroblasts - cells similar to fibroblasts that have the contractile properties of smooth muscles and are responsible for wound contraction

do ligs and tendons have only dense regular ct?

no, the outer surface is irregular ct, continuous with adjacent mm and bones.

reticular fibers can be seen how?

they are not seen in H&E but with silver salts (argyophilic) and with PAS (many carbs)

where do macrophages mature?

they cross ephthilium to enter ct (stroma), where they mature